MOTOBRICK.COM
TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => Project Custom Motobricks => Topic started by: Turbo224 on April 28, 2016, 06:14:16 PM
-
Bought this 90 K75S a few weeks ago and thought I would do a build thread. The plan is to do some sort of cafe/street fighter bike, i'll sort of just start building and see what I end up with. I found this bike on my local classifies and couldn't resist. Fuel injection, single sided swing arm, German engineering, excellent condition, cheap. What's not to love? It has 25K on the clock, the previous owner has owned it since 92. The original parts that I remove will slowly make their way to eBay to help fund my project and hopefully be used to keep other enthusiasts bikes looking nice.
First question. I am going to lube the drive shaft spline first thing as I know that's one of the most important things for these bikes. I have heard that the factory BMW lube isn't very good, is there an aftermarket lubricant I should be using? Do I just need to lube the back end of the shaft, or should I remove the entire shaft and lube the front splines as well?
-
You'll find a lot of technical information here (http://www.motobrick.com/index.php/topic,666.0.html) that can help you with your project. Look under Drive Train for Dr Hubbard's lube explanation as an overview.
The Workshop (http://www.motobrick.com/index.php/board,8.0.html) has component systems divided into categories.
-
Guard dog lube
-
Guard dog makes a lube and a paste, the paste has a higher moly content but the lube is recommended. http://www.beemerboneyard.com/gdmoly2oz.html Honda Moly 60 worked well but is NLA
-
Boron paste. :2thumbup: Don't be a slave to convention.
-
Honda paste is still available but has changed it's name to Honda M77 assembly paste.
Regards Martin.
-
it's all starting to make sense now
-
OMG I'm definitely going to hell, I'll have to purchase an air conditioner for the brick. What with the NGK leads and the 666 I am DOOMED.
-
I still don't understand the desire to take a beautiful bike in great condition and then destroy it. It is like already attractive people going the plastic surgery route and ending up looking far worse than they started. Why not just ride it, enjoy it as is and work to preserve a great piece of motorcycle design?
-
+1 Glacial I love my K75S, some bikes deserve to be left alone unmolested. Custom bikes give a source of fairing parts which are becoming rare.
Regards Martin.
-
After the K1, I think the K75s has the most potential as a collectible. I also think it's the best-looking of the whole K-bike range (totally subjective, of course). It's the only bike in the range to get the pure "S" (not RS) designation by BMW.
So, while this lovely low-mileage, K75s is a an unfortunate start-point.... I call dibs on the windshield and rear rack. :neener: Anybody got a spare top-case laying around?
@Turbo: Just an idea... maybe you could sell the K75s as-is, and buy a K75 standard for less money. That might also help fund your project. Or ride it for a while and see how you like it. I confess that I bought mine (also cheaply) as a beater/commuter. But gosh-dangit.... she had hidden charms and now I really like her. Had I known that in advance, I would have waited for a really sweet one like you got. Now I'm mid-way through a restoration and having a lot of fun with it. Want to play with the appearance a little? Ditch the fork reflectors and tint the turn signal lenses - it does wonders for streamlining the look of the bike.
-
Scud you have me intrigued could you please post pictures showing the tinted lens? A full shot of the bike would also be nice, and also what product you used. Could you do this in a separate post as I don't wish to hijack this one.
Regards Martin.
-
I still don't understand the desire to take a beautiful bike in great condition and then destroy it. It is like already attractive people going the plastic surgery route and ending up looking far worse than they started. Why not just ride it, enjoy it as is and work to preserve a great piece of motorcycle design?
Beauty is always in the eye of the beholder, right? Personally, with the factory plastics on the bike, I think it's quite odd looking. Keep in mind i'm an outsider to the community, so I don't have an emotional attachment to the bike. The longer you are involved with a certain bike/car you will start to appreciate things that you may not have before. Things that may have been quirky or strange start to become endearing after a while. I have had a love affair with the 80's Shelby-Dodge cars for a ling time, and I feel the exact same way about those cars as you do about the K bikes.
In the end its all about supply and demand. If there were a huge demand for these particular bikes, they wouldn't be for sale for so cheap and I would probably be riding something different. That's what has happened in the Shelby-Dodge community. Even though they were limited production, Chrysler built a TON of Shelby inspired turbo cars. Now there are just so many cars available that need to be "saved" from the wrecking yards, but the demand is just too low. If someone really wants to "save" the bike from my hands, i'd listen to any offer from someone who wants to buy it. But other than cutting the rear of the frame, what is typically done to a cafe bike that cant easily be undone?
-
I suspect that the K bikes are at that awkward stage where they are just old enough to be "old" but not old enough to be "vintage".
Yes, they are cheap because the brick engine is so strange. The resultant low price due to the ugly duckling nature of the brick is what makes them so attractive to those looking for a cheap machine to modify, but in the end, that is what dooms the value of what they build. Cafe bikes by definition are carbureted singles or twins, with spoke wheels, a five wire harness and a British nameplate. The K bikes have none of that, and as a result won;t survive in the cafe bike marketplace.
As much as I decry the cafe craze, I must in the end be grateful for the "builders" who are turning these fine machines into future derelicts. By making them uncomfortable to ride and overly hip stylingwise they virtually guarantee that these bikes will be left for dead in about three years. If we are lucky, they will be abandoned to an indoor space away from the sun and rain to collect a lot of dirt and rat shit providing a future source of somewhat useable driveline spares. In addition, the agressive thinning of the herd will make the value of well maintained bricks that much greater when they finally achieve vintage status.
-
Lovely Bike Turbo! So what have you plannedd for your cafe? Do you know what you want to do to it yet?
I just abought K100 myself and am also doing a cafe build. a lot of work ahead of me but I'm really enjoying it so far!
-
Very well said. I actually love the boxy look of the motor on these bikes, that's one of the primary reasons I think they looks so cool naked. Honestly to me these bikes make more sense as a street fighter look which tend to have more aggressive styling and sharp angles. As you said, they really make a poor platform for a cafe bike due to the shear bulk of the motor/trans. As I mentioned in my first post, the single sided swing arm and fuel injection are two pretty cool features for an older bike that's affordable. For me I am building this bike because I love to build things and this bike makes a perfect platform for what I want to do. Odds are I will have fun with it for a few years and then move on to other projects.
-
Lovely Bike Turbo! So what have you plannedd for your cafe? Do you know what you want to do to it yet?
I just abought K100 myself and am also doing a cafe build. a lot of work ahead of me but I'm really enjoying it so far!
Nothing extreme. I'm going to add a new seat/tail section, remove the whole front fairing/headlight/speedo combo and go with a some smaller units.That's pretty much the extent of it. So other than the rear frame being cut, the purists can rest assured the bike won't be "destroyed".
-
I have been gathering parts before I start tearing into the bike and I had a question about using LEDs. I'll be using LED blinkers and an LED tail light. I know I need to use some load resistors for the blinkers to avoid the hyper flash. Do I need to do the same thing for the rear brake light?
-
You should be fine with LED brake light - whether it's a replacement bulb or a whole new LED unit.
The problem with LED signals is because of the flasher units (which brake lights don't have) - the LED signals don't draw enough power to get the OEM flashers' attention. This is, obviously, a non-scientific explanation.
I just put LEDs on a different bike. FWIW, the LED signals in the back work fine with the OEM flasher and incandescent signals up front - so you can mix them.
-
For turn signals you have three options for installing LED bulbs
1) install resistors
2) modify the BMU by cutting a trace and will no longer hyperflash
3) purchase and replace BMU with Kisan signal minder SM-6
You can find references to number 2 if you search
IMHO 1 is a bad choice
Always use LED bulbs of color of the lens, white LED will be very washed out.
-
For turn signals you have three options for installing LED bulbs
1) install resistors
2) modify the BMU by cutting a trace and will no longer hyperflash
3) purchase and replace BMU with Kisan signal minder SM-6
You can find references to number 2 if you search
IMHO 1 is a bad choice
Always use LED bulbs of color of the lens, white LED will be very washed out.
Why is 1 a bad option?
-
Heat, still use as much electricity, etc
-
You will have to modify the BMU if you use LED brake lights. Nothing needs to be modified if you use LED running lights.
-
Thanks for this further discussion. I had to look up BMU (Bulb Monitoring Unit). I had never heard of such a thing... and therefore my earlier advice, based on experience with other bikes, should be ignored.
-
Hey Turbo! look forward to seeing more of your build. I don't plan on building a Cafe but I wanted mine to have more of a street fighter look. Love the way naked bricks look so Keep us posted.
-
If a motorcycle is "cafed" the right way then good. There are many beautiful BMW cafe racers out there, however the majority are butt ugly. In my opinion the K75S with a Corbin gunfighter seat or the BMW model seat that is similar looks very cafe already. The "S" designation has always looked somewhat cafe racer going back to the R90S. I see many converted motorcycles on Craigslist that are for sale at prices way above original models that I suspect never sell. It takes great skill, money, time and dedication to come up with an excellent and appealing cafe racer. Most fail at this, excepting the professionals of course. They lose interest and run low on funds. That said, I wish the O.P. success and await the final result.
-
Interesting variety of comments on whether or not to save or totally change the K75. Here is my take.
I have a mint condition, low miles 1990 K75S which I am keeping as a collectors item, but it is still being regularly ridden, as it is just such a lovely smooth bike. I have found tragkorbs for it and had them colour matched (Onyx Schwartz) it has been brought up to Concours condition and recently won an award for best bike at a BMW rally.
Recently I found a slightly older 1987 bike that was rather sad. It had a leaking fuel tank, which the PO had tried to fix with some "goop" (unsuccessfully). It was missing fairings, had a rear brake reservoir from a car with crappy budged up hoses, blocked extra outlets and various other home made very poorly done jobs. It was pretty sad looking. There was so much corrosion on some parts (battery tray) that they were just not able to be saved. I am turning this bike into a cafe / street fighter look for several reasons.
1. I love the look of the brick motor and the smoothness of the bike.
2. I am getting older and want a lighter bike, but it must be a K
3. This bike will provide spares for others, and help keep them going.
4. I need something to keep me busy over winter.
5. There seems to be a ready market for well executed cafe designs based around the K. Recently a really sharp looking K100 cafe racer sold here for NZD $6800
-
I finally got around to tearing into the bike this week. Purists turn away, you wont like what you see. First thing I did was pull off the front fairing and handlebars. I actually like the look of the belly pan still on there, so I am going to leave that on for the time being. I bought a set of strap-ons and a set of clubman bars because I didn't really know what was going to work. I personally don't like the way strap-ons look, so I started with the clubmans. These are just a set standard 7/8" bars. I didn't want to file out the stock controls in case someone ever wants to put this bike back to original, so I just sanded off the powder coating on the bars. Once the powder coating was removed the controls slide right on the bar. The result? I guess they looked okay, but the shape of these bars just made for a terrible ridding position. Sorry the pictures suck, I was working in my house garage which has terrible lighting instead of the shop.
-
Next I tried the strap-ons. I lowered the front end of the bike a couple inches and had the bright idea that I should just mount the strap-ons to the top of the trees. The results make for a much more comfortable seating position, but the overall look doesn't quite fly. Seeing that I rarely go on long rides, I am going for form over function. I'm going to go ahead and move the bars to underneath the steering head tonight and call it good. On a side note, does anyone know if any steering head from a K100 or K75 will swap onto my bike? Mine is particularly ugly since I cant remove the bar mounts.
-
One suggestion... why not use the bar mounts as the mountings for your instruments (if you are planning on using new ones) - this would kill 2 birds with one stone.
Do you find the riding position too far forward with the Clip Ons?
I am just starting work on a K75S Café build now, and those bars are a continual question in my mind. I want to be able to do some longer runs on it, take it to shows etc, and my ageing body is going to protest too much methinks.
Any others got suggestions on this?
-
One suggestion... why not use the bar mounts as the mountings for your instruments (if you are planning on using new ones) - this would kill 2 birds with one stone.
Do you find the riding position too far forward with the Clip Ons?
I am just starting work on a K75S Café build now, and those bars are a continual question in my mind. I want to be able to do some longer runs on it, take it to shows etc, and my ageing body is going to protest too much methinks.
Any others got suggestions on this?
You actually hit the nail on the head. I'm going to temporarily mount the stock gauges right on top of the head so I can hide the ugly and the bike will be legal. The plan is to use an aftermarket gauge at some point in the near future, so when that time comes i'll replace the head with one of the cleaner units.
Where the strap-ons are located right now is actually okay, I could go on a long ride with how it is setup right now. Once they are mounted below the head it might be a different story. Then again, a cafe racer was never meant to be a long distance bike, they are basically bar hoppers.
-
check your moto geometry and your ride height for whack if you decide to leave those strap-ons like that..
-
How do you do this exactly Johnny?
-
1st... if you caint deploy the sidestand its too low...
-
Most K75s that I have seen (including the two that I own) have quite an alarming amount of lean when on the sidestand. On my wifes bike I have added a 10mm packer under the foot to lessen the angle slightly as she has trouble lifting it up to vertical.
-
As well as the side stand, you might not be able to get it onto the centre stand, if you intend to keep it.
Regards Martin
-
Can't really tell how much you have lowered the forks, but it looks to be significant. That shifts weight to the front and really affects the handling. The geometry between front and rear is messed up with forks too low...........might require a shorted rear shock, various lengths are available. Consider a straight short sport touring bar, which you can find in BMW diameter.
-
Lowering both front and rear significantly will result in less cornering clearance. Might look good but the bike will be slower through the twisty bits.
Regards Martin.
-
I was planning on doing similar to this: http://i.imgur.com/3E8SlyS.png - about 20cm at the front - is that ok without causing whack?
-
I was planning on doing similar to this: http://i.imgur.com/3E8SlyS.png - about 20cm at the front - is that ok without causing whack?
It's going to change the handling, colly, as Martin, Ace, johnny and many articles found researching "motorcycle geometry" have indicated. The significance of the change will be experienced when riding it. You'll need to be prepared to alter it again for safe and practical riding.
A conservative approach as Ace has indicated will be the least costly and safest.
-
Thanks for all the comments. It will definitely be interesting once I get it back on the road. I'm sure I will have to go back and readjust everything to make sure it rides correctly. I changed the strap-ons to below the steering head yesterday and it certainly LOOKS much better. I was worried these would sit far too low for me to ride the bike comfortably. When I removed the seat and rear tail section to start fabbing up a new pan I realized that a much lower seat will make these strap-ons much more livable. I'll be working on a seat pan and rear tail section over the weekend.
-
I have lowered K75s front and rear for women. I noticed a handling change but the women didn't. The K bike kick stands seem to bend fairly easily. They can be straightened out on a press, but over time they will start to bend again. Don't stand on the peg to get on or off if not on the center stand.
-
Worked on the K a little bit this weekend. I removed the rear tail section and got rid of all the brackets and mounting bits I no longer need. I also started working on the new tail section, it's just set in place for now until I decide how I want to attach it. Once I get it mounted I will try to get the bike out in the sun for some decent pictures. Comments and criticisms are welcome. :2thumbup:
-
Spent some time mounting up the headlight and front turn signals yesterday. Standing back and looking at it, I feel like the headlight needs to be lowered. Thoughts?
-
Yes, agreed, the headlight should be centred on the tank when viewed from the side.
What make & model is the headlight from?
Any pics of the clip on mounts and top triple T?
-
Headlight is from a Yamaha MT-03. There are a few pictures earlier in the thread of the strap-ons, I can snap more if you are looking for something specific.
-
A few pictures out in the daylight. Still lots of little things that need to be done, but at least I can ride.
-
I made my own seat cushion and cover. For the pad i used a memory foam gardening mat that I picked up in the gardening section at Walmart. I bought the black vinyl and thread at Hobby Lobby and stitched the pattern myself on a borrowed sewing machine. The base is made from some scrap panel board i had laying around. Cheap, reasonably comfortable, not half bad looking. Also a picture of how I mounted the ignition switch for now.
-
Nice work........the headlight really fits well. Very clean look.